The present invention relates to a method of rolling of heated metallic products to form wires, rods or seamless pipes. The products are generally massive billets with a substantially square, rectangular or round cross-sections. These billets are generally produced by rolling or continuous casting. They must be first heated to a rolling temperature at a level is known and depends on the type of the material. Then the here described rolling process is performed for producing of wires, rods or pipes.
In the known rolling process of this type another rolling apparatus is used for producing of wire or rod than for producing of pipes. For example, this is disclosed in German patents 10 57 048, 10 71 025 and 26 57 823. Such roller apparatuses are composed of relatively great number of specially made aggregates. They require separate space in a sufficiently large hall and substantial costs for their installation and operation.
In order to provide an efficient operation of such rolling apparatus which justify their cost, the apparatuses must be designed for a high production per year. In rolling apparatuses for wire, steel or rod steel, the production must be not less than substantially 300,000-500,000 tons per year. For rolling apparatuses for production of seamless steel pipes, the production must not exceed substantially 150,000 tons per year. This high production however frequently corresponds not to the actual demands, in particular when the apparatus operators have only local markets available. Thereby the apparatuses for production 150,000-250,000 of wire or rod steel and 50,000-100,000 tons of stainless steel pipes per year are desired. With the conventional rolling processes on special rolling apparatuses for wires and rods on the one hand, as well as for pipes on the other hand, it is not possible to operate with lower production quantities, such as for example mentioned above, with substantial efficiency. This is true especially when both wires and rods as well as pipes are to be produced and therefore the conventional methods must use two complete rolling apparatuses, whereby the costs are considerably increased.
Accordingly, it is an object of present invention to provide a method of and an apparatus for rolling which do not have the above mentioned disadvantages, but instead provide for a possibility to produce wires and rods as well as pipes in smaller quantities per year in an efficient manner.
In keeping with these objects and with others which will become apparent herein after, one feature of present invention resides, briefly stated, in that, a rolling of wires and rods on one hand as well as a rolling of seamless pipes on the other hand is performed on the same rolling apparatus, and a part of its aggregates is used both during rolling of wires or rods and also during rolling of pipes.
With this approach the number of the all required aggregates is substantially lower, while some aggregates are utilized both during rolling of wires of rods and during rolling of pipes. This is true especially for the oven, blooming train, some separating devices, the cooling bed and portions of the roller conveyor. The avoidance of a double installation of these aggregates leads to a considerable saving. Also, with such a method a substantially smaller place is needed, so that the halls can be substantially shorter than in the case with conventional rolling in two separate rolling apparatuses. Frequently, an already available hall suffices. Moreover, the same personnel can be used both for the wire/rod production and also for the tube production. Furthermore, offices, infrastructure, shops, energy and media, such as for example current, oil, water, pressure air and the like are needed only for a single rolling apparatus. As a whole, a drastic reduction of cost is obtained, whereby wires, rods and pipes can be produced in an efficient manner even with low production numbers per year.
It is also another object of present invention to provide a rolling apparatus for performing the inventive method. In the rolling apparatus behind an oven and a transverse transporting device, near one another, a rolling line for wires or rods and a rolling line for pipes is arranged, which are united then in a common rolling line with at least one separating device, behind which a cooling bed and/or other finishing devices are arranged. The arrangement of the both rolling lines near one another does not mean that they must extend exactly parallel to one another, while of course it can be advisable in many cases. The rolling lines also must not necessarily form a throughgoing straight line. Billets for wires, rods and pipes can be brought to a rolling temperature in a common oven for both rolling lines, and in any desired row sequence. The transverse transporting device provides the supply of each billet to the rolling line provided for it. Both rolling lines can be operated alternatingly. Therefore, there is a flexiblity with respect to the exchange of programs when within a few minutes the inventive rolling apparatus must be converted from a wire/rod production to a tube production and vice versa.
The corresponding non-used rolling line can be prepared meantime for its next rolling, for example with another cross-section than before. Thereby also maintenance works and repairs can be performed, without disturbing the rolling operation which takes place in the other rolling line and without interrupting the same. Under certain conditions, such as for example when a rolling stand is dispensed with in the region of the common rolling line and a correct determination of the input time point and through going speed, the both separate rolling lines can operate also simultaneously. The above mentioned finishing devices are such aggregates which are used for example for cooling, transportation, testing, collecting, dividing and packing of the finally rolled product.
It is recommended that in the common rolling line the separating devices including a saw and a shears are provided. The saw is better suitable for separating the rolled pipes, while in contrast the wires or rods are better separated with the shears. Both separating devices must be however suitable for separation of continuously running products.
In an apparatus with a cooling bed and other finishing devices, it is in some cases advantageous to provide behind the separating device or devices of the common rolling line but before the cooling bed, a deviation to other finishing devices. All products which can not be supplied directly to the cooling bed since, for example it is wound or looped or further rolled, can be supplied to the corresponding following devices. For this purpose the deviation must be adjusted selectively in one or another direction.
In accordance with a further embodiment of the present invention, behind the separating device of devices of the joint rolling line but before the cooling bed, deviation to rolling block for final rolling of wires can be arranged. This is first of all required during production of wires with a relatively small diameter.
In many apparatuses it is advantageous when in the common rolling line before the separating device or devices, a reducing or sizing rolling block or train is provided. The later differs from the reducing and sizing rolling blocks substantially only by the individually driven rolling stands arranged with a greater distance from one another. With these aggregates both rod-shaped and also tube-shaped products can be finally rolled. Therefore, especially low tolerances and all desired outer dimensions can be provided. Preferably, the rollers are adjustable in a radial direction. Therefore in the event of small changes in the outer diameters no exchange of rollers is needed, but instead only an adjustment of the same. In the event of great changes of the outer diameter, a fast exchange of the rolling stand is performed, and the newly introduced rolling stand can be provided in a stand shop with suitable rollers having a finally adjusted calibrating opening. In this process it does not make any difference whether the changes are performed from a smaller outer diameter to a greater one, or vice versa.
It is especially recommended to arrange a blooming train composed of at least two rolling stands behind the oven and before the transverse transporting device. The blooming train rolls the billets both for the rolling line for wires or rods and also for the rolling line for pipes, and a round cross-section is produced. It is advisable to provide the rolling stands of the blooming train with radially adjustable rollers. Moreover, it is recommended to form the blooming train as a reversible rolling train.
While the blooming train in many cases prepares the product for introduction into the separate rolling lines, also the blooming train can be utilized as a finishing train when rods must be rolled with especially great outer diameters. In such a case it is advisable when behind the blooming train and before the transverse transporting device, a blooming train cooling bed is provided. The finally rolled product from the blooming train can be cooled there, collected and discharged from the rolling apparatus.
It is further recommended to provide a separating device immediately behind the blooming train. With the such an arrangement is possible to subdivide the product rolled in the blooming train to desired lengths. In particular the rolling line for pipes requires shorter preliminary material that normally produced in the blooming train. This separating device serves however also for cutting off of the products exiting the blooming train, so that a substantially flat end surface is obtained to provide an unobjectionable perforation of the products in the rolling line for pipes.
In many cases it is advantageous to arrange a post-heating device behind the transverse transporting device in the rolling line for pipes. With this device the temperature of the products can be brought exactly to such a value which is required for the subsequent perforating and stretching steps.
In the rolling line for pipes a piercing mill, an elongating mill and a stretch reducing mill are arranged one after the other. Basically all known types of these aggregates can be utilized.
It is however advantageous when the stretching rolling stand is provided with a known planetary inclined rolling stand which is located only at a small distance from the stretch reducing mill. With a planetary inclined rolling stand, the rolling product does not rotate during the rolling around its longitudinal axis and therefore can be introduced with its front end portion into the subsequent stretch reducing mill, when a rear end is still rolled in the planetary inclined rolling stand. This makes possible in an advantageous manner a small distance between both rolling aggregates and thereby a short total length of the rolling line for the tube production.
In accordance with the recommended embodiment of the invention, the rolling line for wires or rods and the rolling line for pipes are joined to a common rolling line in the region of their rear longitudinal portions, by means of a transverse pusher. The common rolling line basically can be arranged in alignment with the rolling lines for wires and rods or the rolling line for pipes. A selection of the arrangement depends on the length of the product at this location. The shortest products are transported the best through the transverse pusher, and thereby it can be held as small as possible.
It is advantageous to provide a saw in the rolling line for pipes behind the last rolling stand. The pipes can be cut there to their final length. If thereafter they are supplied via the transverse pusher of the common rolling line, then it can be maintained substantially smaller than known otherwise.
In the rolling line for wires or rods, a number of rolling stands are arranged one behind the other, which at least partially can be assembled to one or several rolling blocks. Moreover, between the rolling stands or rolling blocks, shears are provided. They serve for cutting off of disturbing ends, and during interferences also for comminuting the rolling product.
The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.